The present invention relates to torque transmitting devices in general, and more particularly to improvements in separable torque transmitting connections between rotary driving and driven members, for example, between a shaft and the core of a bobbin, reel or the like. Still more particularly, the invention relates to improvements in torque transmitting connections of the type wherein a male coupling element of the connection is insertable into or removable from a complementary socket which is defined by a female coupling element and wherein the insertion or withdrawal of the male coupling element takes place at right angles to the axes of the coupling elements.
It is already known to couple a rotary driving member with a rotary driven member by means of a torque transmitting connection including a female coupling element which defines a socket and has a lateral opening for insertion or removal of the male coupling element which has one or more flats to ensure that it cannot rotate with reference to the female coupling element. One of these coupling elements is provided on the driving member and the other coupling element is provided on the driven member. Connections of such type can be employed with advantage in winding or unwinding machines for textile materials or the like. Reference may be had to German Pat. No. 917,592 which discloses a separable connection between a driving member and a driven member in a tilting bearing. Similar connections can be used with advantage in so-called sliding bearings. Thus, two male coupling elements at the ends of a reel or the like can be inserted sideways into a pair of complementary female coupling elements, and each male coupling element is thereupon held against rotation relative to the associated female coupling element by a pivotable or shiftable holding or blocking device so that the female coupling elements can transmit torque to the properly inserted reel. The flats of the male coupling elements ensure that such coupling elements cannot turn in the sockets of the respective female coupling elements, i.e., each flat can transmit at least some torque when the female coupling elements are rotated.
In presently known connections of the above outlined character, each male coupling element is formed with several flats. For example, each male coupling element can have a polygonal cross-sectional outline with four facets. This ensures reliable transmission of torque, i.e., the male coupling element can be received in the complementary socket of the associated female coupling element without any slippage. In other words, it is simple to establish a reliable form-locking connection between the external surface of a polygonal male coupling element and the complementary surface bounding the socket of the female coupling element. However, such connections also exhibit a number of drawbacks, especially as concerns the manufacturing cost. Thus, if the polygonal male coupling element is to fit into the socket of a female coupling element without appreciable play, the two coupling elements must be machined with a very high degree of precision, not only for the purpose of ensuring that the male coupling element will accurately fit into and will not wobble in the socket but also to ensure that one of these elements is coaxial with the driving member and the other element is coaxial with the driven member. In addition, it is difficult to ensure accurate engagement with the pivotable handle which must be centered on the driving member with a high degree of accuracy. Another drawback of such conventional connections is that they do not allow for interchange of reels, i.e., for insertion of male coupling elements on any one of a large number of reels into a pair of female coupling elements, unless the tolerances in the dimensioning of surfaces in the sockets and on the male coupling elements are so pronounced that they prevent reliable transmission of torque to the inserted reel. Still further, insertion of polygonal male coupling elements into the sockets of female coupling elements presents many problems because the male and female coupling elements must be moved to predetermined positions relative to one another prior to the inserting step, especially if each male coupling element has one or more pairs of parallel flats.
Attempts to overcome the drawbacks of the just described conventional connections include the provision of male coupling elements having a triangular cross-sectional outline, or the positioning of square male coupling elements in such a way that they are insertable into the sockets of the female coupling elements with one of their corners or edges leading. Such connections are expensive and the male coupling element tends to "climb" out of the socket of the female coupling element when the connection is in the process of transmitting a pronounced torque. The making of round or substantially round male coupling elements involves a greatly reduced expenditure and renders it possible to ensure a more accurate axial alignment between the two coupling elements as well as between the male coupling element and the part to which such coupling element is connected. However, a truly round male coupling element is incapable of transmitting or receiving torque, especially pronounced torque.